f01bsf

f01bsf © Numerical Algorithms Group, 2002.

Purpose

F01BSF LU factorization of real sparse matrix with known sparsity pattern

Synopsis

[a,w,rmin,ifail] = f01bsf(n,nz,a,ivect,jvect,icn,ikeep,idisp<,grow,eta,...
abort,ifail>)

Description

 
 This routine accepts as input a real sparse matrix of the same 
 sparsity pattern as a matrix previously factorized by a call of 
 F01BRF. It first applies to the matrix the same permutations as 
 were used by F01BRF, both for permutation to block triangular 
 form and for pivoting, and then performs Gaussian elimination to 
 obtain the LU factorization of the diagonal blocks.
 
 Extensive data checks are made; duplicated non-zeros can be 
 accumulated.
 
 The factorization is intended to be used by F04AXF to solve 
                                             T   
 sparse systems of linear equations Ax=b or A x=b.
 
 F01BSF is much faster than F01BRF and in some applications it is 
 expected that there will be many calls of F01BSF for each call of
 F01BRF.

Parameters

f01bsf

Required Input Arguments:

n                                     integer
nz                                    integer
a (:)                                 real
ivect (nz)                            integer
jvect (nz)                            integer
icn (:)                               integer
ikeep (5*n)                           integer
idisp (2)                             integer

Optional Input Arguments:                       <Default>

grow                                  logical  1
eta                                   real     1e-4
abort                                 logical  1
ifail                                 integer  -1

Output Arguments:

a (:)                                 real
w (n)                                 real
rmin                                  real
ifail                                 integer